Concrete-strength regulator



Jan. 24, 1928. 1,656,904

J. G. AHLERS CONCRETE STRENGTH REGULATOR Filed April 6, 1927 2 Sheets-Sheet 1 INVENTOR w 6. W

I 765 ATTORNEYS Jan. 24, 1928. 1,656,904

J. G. AHLERS CONCRETE STRENGTH REGULATOR Filed April 6, 1927 2 Sheets-Shut 2 58 WATER z I 7 I+|250 H750 I+i25o -250: l -75!) l +1500 +|0o0 +50 '-soo 00 o i CEMENT suvma L160 7o .:60 JIEOIMOIBO' 20.10 I00 90 so ,70 .60 50 .40 so ,20 +1500 MOISTURE COMPENSATION WEIGHT L85. OF WATER L) \n 14-500 A F I ll 2 JOB 2 S CONSTANT o: lo

WATER-CEMENT RATIOS lNVENTOR 14 ATTORNEY$ Patented Jan. 24, 1928.

UNITED STATES PATENT GFFICE.

CONCBETE-STRENGTH REGULATOR.

Application filed April 6,

This invention relates to the making of concrete-tor use in constructing buildings and other structures and more particularly to concrete strength regulators. The improved apparatus for regulating the strength or" concrete ot' the present invention 13 snu lar to the apparatus described in my apphcation for concrete making, Serial No. 77,722, filed December 26, 1925.

Concrete comprises a mixture of cement, water and aggregate materials. It was long thought that the strength of concrete was primarily dependent not only upon the quality of the aggregate material but upon the ratio of the amount of aggregate material to the quantity ot cement.

As a result of extended investigations at the Lewis Institute, Chicago, Illinois, it has been established that the strength of concrete depends primarily on the ratio of water to cement. The results of tests carried on during these investigations were plotted against coordinates representing the com pressive strength of the concrete in pounds per square inch at 28 days, and the water: cement ratio. These curves were substan tially parallel. Each of these curves represented certain actual working conditions; that is, the other influencing factors such as the quality of cement, the quality or cleanliness of aggregates, and the length of time, thoroughness ot mixing and handling l't. maiued constant for each curve, the ratio of water to cement alone being varied.

For any particular job it is possible to establish a similar curve depending primarily on the the quality of cement and kind and cleanliness of aggregate to be used. Furthermore, it will only be necessary to locate one point on this curve, for the curve will be substantially parallel to the Lewis Institute curves.

The most convenient point to locate is for a ratio of water to cement equal to one, (i. e. one cubic foot of water or 7 gallons to one bag of cement containing in the United States 1 cubic foot of cement and weighing 94 pounds). iVe will refer to this point a." the job constant and to the curve as the job curve.

One of the objects of the present invention is to produce a regulator which will assure the correct mixing of water and cement a-c-' cording to the requirements of the particular 1927. Serial No. 181,355.

job even when operated by tors.

Another object is toproduce a regulator, which, when the job constant has been ascertained, will indicate the resulting compressive strength of the concrete tor any setting of said regulator.

Another object is to'produce a regulator which may be set so as to compensate for the moisture content of the aggregate and in which the compensating scale will read directly in pounds of water.

The invention consists briefly in applying the water ratio theory as developed by the Lewis Institute to an apparatus through which the amount of concrete which is fed to the apparatus, will control the amount of water supplied to the apparatus.

According to the invention, an appropriate amount of cement for a given batch of concrete is introduced into a solids receptacle which is operatively associated with a balance. lVater is supplied to a liquid receptacle operatively arranged to balance the solids receptacle and the supply of water is automatically interrupted when the contents of the two receptacles attain a predetermined ratio of water to cement. The balance consists of arms supported by a knife edge fulcrum. These arms support the cement hopper and the water receptacle. Compensating weights are slidably mounted on said arms so that the moisture content of the aggregate may be easily compensated by adjusting the position of the weights. Means are provided so that the contents of the cement hopper and the water receptacle may be easily discharged into the concrete mixing apparatus, the balance arms being prevented from tilting during the discharge.

The aggregate material is then added to the mixer until the mixture has attained the desired workability or plasticity. The amount of aggregate added will not materially affect the strength of the concrete so long as the mixture remains sufficient-1y plastic to be poured.

The strength of the resulting concrete depends therefore on the setting of the regulator which automatically regulates the mixture of cement and water for any desired strength of concrete, the job constant having been ascertained.

The regulators operation is extremely unskilled operasimple and it may be operated by unskilled laborers, without aiiect-ing the accuracy of its mixing, requiring only the preliminary setting at'thebeginning of a job and the occasional adjustment of the compensating weight to accord with the variations of moisture in the aggregate.

The regulator, therefore, insures within narrow limits a certain, fixed strength of the resulting concrete and permits using the most economical mix in attaining'that desired strength. I

For an example of apparatus adapted for carrying out the invention, reference is made to the accompanying drawings, in which Fig. 1 is a side elevation,

Fig. 2 is a plan view;

Fig. 3 is a vertical section taken along line 3-3 of Fig. 2;

Fig. e is a detailed view ofthe compensating weight and'guide and the mechanism for locking. the liquid receptacle in adjusted position; and Y Fig. 5 is a diagrammatic view of the concrete strength regulator and strength curve.

Referring to these drawings and in particular to Fig; 1, a supporting frame-work 10 of suitable steel shapes and adapted to be fixed to a foundation of wood or cement, supports the various elements of the regulator.

At the left hand end of the framework 10, two knife edge supports 11 are provided as a fulcrum for a balance beam 12. This balance beam 12 comprises a rectangular frame, having two spaced longitudinal chan nels 13 and 14, suitably connected at their endsby cross beams 15,16.

At the left hand of the balance beam there is a cement receptacle or hopper 17 pivotally secured to the side channels 13, 14 at 18 and 19' respectively. This hopper is adapted to receive cement and is equipped with a spout 20 by which the cement can be dumped into the mixing apparatus at the proper time by rotating the hopper about its pivots with the aid of its handle 21. The handle 21 has a lateral bar 22 which will strike against balance beam 12 when hopper 1'? has reached a discharging position and will prevent further rotation of hopper 17 about its pivot. in Fig. 1 the hopper is shown in its discharging position in dotted lines. The sectionsof channels 13, 1a which adjoin the hopper are provided with butter plates 23 which protect the channels and also serve as a convenient rest for the cement tainer restg on the top flange or said channels, permitting a sliding motion of container along said channels. It will be noted, however, that hopper 17 is fixed to the channels and the distances between the knife edges 11 and the hopper pivots 18 and 19 is not adjustable and always remains constant. 7

The container 2% may be locked in any position to which it has been adjusted by means of plungers 26 shown in Fig. 4. The plungers 26 are pivoted to handles 27 which are in turn pivoted to the container at 28 and 29. The two handles 27 are connected at their ends by a rod 30; lifting 'rod' 30 the handles will rotate about their suitably attached to angle beams 25, said angle beams being provided with an opening below said guides to permit the plungers to pass therethrough. The top flange of channels 13, 14: are provided with openings adapted to receive the plungers, said openings being situated at determined distances from knife edges 11. When 'rod 30 is lowered plungers 26 will pass through openings "2 in the channels thus locking the container in the desired position.

In order to slide the container to a different predetermined position, plungers 26 must be raised by lifting rod 30, when the container will be free to move along the channels until rod 30 is again lowered, locking the container in a predetermined position. The guides 31 are provided with pointers Water is supplied to container 24: through the supply pipe 33, automatic valve-3i and the pipe The automatic valve 3 1 is supported by an angle 36 projecting from right hand end of supporting frame-work 10. This valve is biased to the closed position by means of a weight 37 carried by an arm 38 that is secured to shaft 39 of the rotatable member of the valve. In the position. shown in the drawings the valve is closed and weight 3'7 rests on a suitable support 4-() projecting from framework 10. To open the valve, arm 38 is raised and it is held in this raised position by means of a suitable latch mechanism. This mechanism includes a hook forming a part of arm 38 and so disposed thereon that, when the valve is in the open position, hook 41 will occupy a horizontal position.

The valve 3% is held open by the engagement of the right hand vertical wall of the notch of hook atl with a latch pin 42. This latch pin 12 is carried by an arm a3, said arm being pivoted to the web of a 2 upright which is bolted or riveted to the balance beam 12. A spring 15 is attached to the end of arm 41-3 on the other side o1 pivot and tends to lower left hand end of arm 13 and consequently to raise the right hand end of arm 13 carrying the latch pin.

pipe 35, arm 38 is moved upwardly from the closed position, thereby rotating valve shaft 39 and hook ll in aclockwise direction. As arm 38 approaches the opening position the sloping race of hook 4E1 slidingly engages latch pin 42, thus depressing latch pin 42 and pivoted arm d3 against the action of the spring. hen arm 38 reaches the wide open position latch pin 42 snaps upwardly into the notch of hook 41-1 and holds the valve in the open posit-ion only so long as the weight of cement in the hopper is heavier than the weight of water in the container. As soon as the water in the container starts to overbalance the weight of cement in the hopper, the right hand portion of balance beam 12 moves downwardly and carries Z upright ia, arm a3 and latch pin 42 with it. The latch pin 42 is thus moved out of the slot of hook 41 allowing weight 37 to descend against stop 40 and to close the valve. When the right hand end of balance beam 12 has descended sufiiciently to release hook 41 it will have reached a horizontal position where the right hand end of the balance beam will rest against supporting framework 10 and thus further downward motion of the balance beam will be prevented. W'hen the balance beam has been emptied of its cement and water, a new batch of cement is added to the hopper causing the right hand end of the balance beam to rise until it comes into contact with stops 4? which consist of angles bolted to the supporting frame-work. In this slightly inclined position or the balance beam, the latch pin 12 carried thereby is in position to enthe notch in hook 41, as arm 38 is raised to open the valve. As the container is filled, the container end of the balance beam will descend until it reaches a horizontal position when the weight of water will just over-balance the cement and the valve will be automatically closed as described.

In order to discharge the water from the container, a valve 18 is arranged to close an opening in the bottom of the container and the valve is lifted by hand by the pivoted lever are connected thereto by the link 50.

The water thus released is discharged into a conduit 51 which leads over to the left end of the apparatus so that both the water and the cement may be discharged at approximately the same point into the mouth of the mixer. In order to provide for the adjustment of container as along balance beam 12, conduit 51 has an elongated open in 52 so as to receive the water from the valve 48 at any position of the container upon the balance beam.

In order to compensate for the moisture content of the aggregate the balance beam is provided with two sliding weights 5;), 54. Referring to Fig. a, angles are rivet-ed to channels 1?), 1 1 and the stems of T beams 56 are riveted to angles 1%. The T beams 56 serve as a guide and support for weight-s 53, 5a.

In employing this apparatus to carry out the process of the present invention. it is lirst necessary to obtain the job constant (i. e. the strength of resulting concrete tor a ratio of water to cement equal to one). From the job constant (see Fig. as indicated above, the job curve may be drawn, the coordinates being the strength of corcrete and the ratio of water to cement. For any desired strength of concrete, from the job curve the corresponding water ratio to produce that strength may be ascertained. As the job curves for different jobs are substantially parallel, a certain decrease in the water ratio, for instance from 1.00 to .'L-) -l-, will always cause the same corresponding increase in strength of the concrete. that is, an increase of 250 pounds per square inch, whatever the actual value of the job constant may be in the different jobs. In this manner, when the container set on the balance beam so that the water ratio will be .Sel, the strength of the resulting concrete will be the value of the job constant plus 5250 pounds per square inch. Likewise, for a setting giving a water ratio of 1.00 the strength of the resulting concrete will be the value of the job constant minus 250 pounds per square inch.

A scale 58 may be added to the balance beam to show what the ratio of water to cement will be for any position ot' thrcontainer. The values on this scale. are ascertained by trial. Furthermore, the different water ratio values on this scale may be transposed into the values of the strength of concrete above or below the job constant. Indicating the job constant as S, for instance, tor a water ratio of 1.00 the strength of concrete will be S minus 250 pounds, for a water ratio of 1 the strength or concrete will be S, and for a water ratio of .9st the strength of concrete will be S plus 250 pounds per square inch.

Let us suppose that for a particular job we ascertained the job constant to be 2050 pounds and that the strength required is 1800 pounds. The difference between the job constant S and the required strength minus 250 pounds. i e would then adjust container on the balance beam until the pointers 32 mark the point "250 on the scale, and then lower the rod 30, locking container in this position. -We may now aggregate added provided the mix remains ,sufiiciently plastic and workable.

However, it the aggregate contains moisture, as it almost invariably will, it is necessary to compensate for it. The moisture content is ascertained by drying and cooling represamples of the aggregate, weigh,-

g the same before and after the drying operation. It the moisture content is, for instance 3% and the average amount of water is 1300 pounds, then there is pounds f water in the aggregate and this aniont compensated "for bythe regulator.

This compensation ei'i'ected by two weights 53, which may he slid along T beams 56. The weight for instance, is used simply as a counter or balance weight for weight 54-. A scale in pounds is inscribed on the T beam 50 for the weight starting near the letthand end of balance beam and ending near the right hand end of balance beam. lVhen weight 54 is on the Zero mark of the scale near the left hand end of the balance beam the counter weight 53 is situated on the right hand end of the balance beam an equal distance fron'rthe knife edges 11 so as to exactly counterbalance the weight of weight-5%. The counter weight is fixed in this position. rrs the compensator weight is moved along the scale towards the right hand end of balance beam the counter Weight overbalances the compensator weight 5% and when the compensator weight 5d passes to the right hand side of the balance beam both compensator weight and the fixed counter weight 53 act on the right hand end of balance beam. The scale is graduated in pounds in such a manner that for any setting ot'tlie compensator weight 54- it willindicatethe C0111- bined el'i'ect ot the weights 53, 54: on the container when the container is at the S or job constant po ition which is the same as the position for a ratio of water to cement equal to 1.00. The size and weight of the weights 53, 54 may be so adapted that the range of the compensation scale will meet all actual job values.

The moisture compensation s'cale'59 is correct only when the container is at the position S for a strength otconcre'te equal to the job constant, i. e. for a ratio of water to cement equal to 1.00. For "example, it the container is moved to a position along the balance beam for a strength'df concrete equal to S minus 250 pounds corresponding to a water ratio of 1.06, the values the scale.

without having aer tor "on the compensation 'scalewill have to be corrected to correspond to this "new position of the container 1. e. the com jensatl'n n. weight Wlll have to be moved in order to have the same "effect on the container in the new position of the container as it had 1n the old.

per batch was 39 pounds, it the conta1ne'r is in the position S the compensator weight would beset directly on the graduation onthe scale marked 39 pounds; if the container is in the position 250, the compensator weight is set about half way between the graduations on the scale marked '86 pounds and '37 pounds, as 39 pounds multiplied by the'correction factor .94 for this position or the container, gives 36.66 pounds. A table is placed on the outside or the container indicating the correction factors for the different settings of the container.

By means of these arrangements the setting of the regr'ilator is greatly simplified without afiecti'ng its accuracy.

To summarize the method of'opera tion, let us suppose that the job constant ascertained is 1850 pounds and the required strength of the concrete is 2100 pounds. The diilerenc'e between "the job constant and the required strength 'is +250 pounds. The container will beset so that-pointerli marks +250 on Let us further assume that the moisture content-0t the aggregate for each batch is pounds. By referring to the table on the container, we find the correction "factor for asetting of the container at +250. The factor for this setting is 1.06. Therefore we will set the compensating weighton the graduation of the compensation scale marked Ve may now turn the regulatoroverto unskilled operators and feel assured that the resulting concrete will 'meet the acquired strength requirements.

The use of this regulator will satisfy the architect that the concrete will be of the required strength'and the contractor that he is using the most economical m'irrto meet the requirements. 7

Very often in thesamejob the requirements vary, i. e. for part ot-the building the required strength of concrete will be only 1850 pounds, for instance. To meet this change in requirement the container is set so that pointer 32 marks S on the scale and thecompensato'r weight is moved from graduation 58pounds to 50 pounds.

The improved regulator of the present invention will "withstand rough treatment I its accuracy noticeably affected.

Iclaim-z v '1. 1n ac'on'cfete strength regulator, a su porting frame, parallel balance arms fulcrumed upon said frame, a cement hopper pivotally secured on said balance arms on one side of said fulcrum, a water container slidably carried on said balance arms on the opposite side of said fulcrum, and a strength scale on said balance arms to indicate for any setting of said container on said balance arms the compressive strength of the concrete resulting from mixture of cement and water in said hopper and container, and means for limiting the motion of said balance arms about said fulcrum.

2. A concrete strength regulator comprising a cement hopper, a water container, said hopper and said container being operatively associated with a balanci mechanism, valve controlling admission of w ter to container and actuated by said balancing mechanism so that said valve will be closed when said hopper and said container reach a balanced relationship, said container being capable of adjustment on said balancing mechanism so as to vary the ratio of wa or to cement when said container and said hopper reach a balanced relationship, a srength scale for indicating the strength of the resulting concrete for any position of the container on said balancing mechanism, compensating weights slidably carried by said balancing mechanism and adapted to compensate for the water content of the aggregate material to be mixed with the water and cement, and a compensation scale adapted to indicate for any position of said weights the compensating effect of said weights for a given position of said container on said balancing mechanism.

3. In a concrete strength regulator, a supporting frame, two balance arms connected by cross members and fulcrumed upon said frame, means on said supporting frame for limiting the pivoting motion of balance arms about the fulcrum, a cement hopper pivotally secured to said balance 2tlll'lS,'2l water container slidably carried by said balance arms, a strength scale on said balance arms to indicate for any position of said container on said balance arms the strength of concrete resulting from mixture of cement and water in said hopper and container, compensating weights slidably carried by said balance arms, and a compensating scale adapted to indicate the compensating effect of said wei hts on said container for a predetermined setting of said container on the strength scale.

4. In a concrete strength regulator, a supporting frame, two parallel balance arms fulcrumed upon said frame, a cement hopper pivotally secured on said balance arms on one side of the fulcrum, a water container slidably carrieo on said balance arms on the opposite side of the fulcrum, means on said supporting frame for limiting the oscillahopper pivot-ally carried between said bal ance arms, a water container slidably carried between said balance arms, said supporting frame being adapted to limit the balancing motion of said balance arms, an arm pivoted to said water container, a plunger operatively associated with said arm, one of said bal ance arms having openings for receiving said plunger so that the container may be locked in any desired position by lowering said arm carrying said plunger.

6. In a concrete strength regulator, a supporting frame carrying two knife edges, two balance arms connected by cross members and pivoted on said knife edges as a fulcrum, means on said supporting frame for limiting the movement of said balance arms about the fulcrum, a cement hopper pivotally secured to said balance arms on one side of the fulcrum, a water container slidably carried by said balance arms, an arm pivoted ateach side of said container, plungers operatively associated with said arms, said balance arms having openings to receive said plungers, and a cross member rigidly connecting the outer ends of said arms so as to actuate said arms simultaneously to lock the container in any desired position on said balance arms.

7. In a concrete strength regulator, a supporting frame, two parallel balance arms con nected by cross members and fulcrumed upon said frame, a cement hopper pivotally secured between said. balance arms, a water container slidably carried by said balance arms, said frame being adapted to limit the motion of said balance arms about the fulcrum, an arm pivoted to said water coniainer, a plunger operatively associated with said arm, one of said balance arms having openings to receive said plunger so that the container may be locked in any desired position by lowering said arm, a strength scale on said balance arms to indicate the strength of the concrete resulting from mixture of cement and water in said hopper and said container for any position of said container on said balance arms, said balance arm having the openings therein arranged to correspond with the graduations on said strength scale.

8. In a concrete strength regulator, a supporting frame provided with two knife edges, two parallel balance arms connected by cross members and pivoted on said knife llO edges a fulcrum, a cement hopper pivotal,- ly secured between said balance arms, a water container slidably carried by said balance arms, a handle on said hopper for, ro-

tating said hopper around its pivot, saidhan- (he being provided with aprojecting element which is adapted to strike against said balancearms \vhenthe hopper is in its dischargingposition whereby said hopper is preventedfrom rotating beyond this position.

9. In a concrete strength regulator, a supporting frame provided with two knife edges, two parallel balance arms pivoted on said knife edges as a fulcrum, a cemeuthop:

member on said frame and adapted to act as a rest for sald Weighted arm when the valve isclosed, a latch mechanism for holding the weighted arm in open valve position until saidhopper and said, container reach a balanced relat1onship,and means, on sa1d-sup porting frame for limiting the balancing a, valve, controlling admission of Water to said; container andactuated by said balancing mechanism so. that said valve will be closed when said hopper and said container reach a balanced, relationship,said container being capable of; adjustment on said balancing mechanism so as to vary the ratio of water tocement when said container and said hopper reach a balanced relationship, and a compensating weight slidably carried by said balancing mechanism and adapted to com: pensate for the water content of the aggregatematerial to be mixed with the cement and Water.

In testimony whereof I; aflix my signature.

JOHN GORDON AHLERS. 

